3 speed truck transmission

[cmtatsch]

Guys could somebody help me identify the 3 speed. It is a 3 speed top shifter with a pto and pretty heavy. I have the casting number off the side but cant find anywhere to find out what it is. Also I know that it will bolt up to a bellhousing that also had a NP420 installed. Thanks for any help, CHris. cmtatsch@alltel.net

[pflaming]

Sounds like maybe a PTO setup for a dump truck, but I would think it would be on a four speed. Maybe it is a setup for a PTO farm equipment of some sort. They used pickup trucks for a lot of things years ago. I remember having to back up the truck to pull a well.

[Merle Coggins]

I've never heard of or seen a 3 speed with a PTO. Are you sure it's not a 4 speed? There were a couple different types of 4 speeds, and the cases are different, drain plug and PTO location is different. One is a spur gear trans and doesn't have syncronized shifting. The other one has helical cut gears and is syncronized. I believe they are both New Process 420 transmissions.

Merle

[cmtatsch]

I have an Np 420 and this does not look anything like it. I have went thru the gears and all that I can get is 3 forward and reverse. On my early Np420 it has the 2 bearing cape front and rear for the bottom idler, but on this on trans it uses needle bearings. also this trans has a drain plug that angles down.

[Merle Coggins]

The trans in my truck is the earlier 4 speed, non-syncro unit and the drain plug points down at an angle. Unfortunetly I don't have any good pictures of it. I also have another later 4 speed, syncro type trans that has the drain plug pointing straight back.

Without having them side by side and comparing them, I do believe the cases are different. I also believe I read about the differences in my parts manual. Also the gear clusters and many other things are different between the two.

When you say you can only find 3 forward gears and reverse, where is reverse in relation to the 3 forward gears? Is it below 3rd like a typical "H" pattern 3 speed, or over and back like on the 4 speed?

Merle

[grey beard]

Merle is right - all four speed boxes have a spring-loaded detent position to either the right or left of center neutrl position. A three speed box has no spring detent on either side. This can be determined just by feeling the shift lever with the box installed in the truck. If there is no spring-loaded detent on either side, it is a three speed. In more than forty years' experience as a mechanic, I have never seen a pto unit on a three speed box. JMHO

[Tony WestOZ]

I don`t know if these where used in the US. We had them in OZ for the 2-3 ton trucks.

Known as a Type F (helical cut gears).

Suppose to be a 4 speed box but I cannot find them all.